The present invention provides a process for joining dilute copper based alloys to be used for electrical conductors, such as wire and cable, to produce long coils of wire and shaped wire products. The process achieves high strength welds close to parent properties and characteristics without the need for heat or mechanical treatment to restore properties to the weld and its adjacent zone typical of current welding practices.
Electrical connector and conductor applications which are not satisfied by commercially pure copper are increasingly being replaced by dilute alloys of copper. These alloys have less than 20% alloying content (80% copper based) and usually have less than 5.0% alloying content. The alloying addition is designed to strengthen the structure by precipitation and/or particle or work hardening, thereby only minimally impacting conductivity.
The process involved in making or maintaining long coils of these alloys requires coil butt welding. Due to the nature of the drawn and shaped wire forming processes or cabling procedures and to assure economics, these end butt welds should desirably be done so as not to degrade the metal properties in the weld region. Naturally, also, the weld structure should be as close to the parent structure in mechanical and electrical properties as possible. Specifically, a weld zone of heat affected metal resulting from a fusion bonding process would adversely affect mechanical properties and especially electrical conductivity. Cold pressure welding, which is significantly more difficult to do in large or non-round configurations, also yields significant increases in strain hardening with concomitant loss in ductility in the weld zone.
One can overcome the above deficiencies by subsequent heat treating procedures or cold work on the entire coil, but this is expensive and time consuming and can create other problems.
Accordingly, it is a principal object of the present invention to provide a process for joining copper alloy electrical conductors in strip, rod or wire form.
It is a particular object of the present invention to provide a process as aforesaid which provides a joined copper alloy conductor having good strength and conductivity properties.
It is a still further object of the present invention to produce coils of joined copper alloy conductor.
It is also an object of the present invention to provide a process as aforesaid which is convenient and expeditious to practice.
Further objects and advantages of the present invention will appear hereinbelow.